Tomographic imaging devices or cameras are frequently used to assist in the diagnosis and treatment of a variety of anatomical structures and physiologic functions within the body of a subject patient, while minimizing the need for invasive procedures. Such devices typically utilize scanners that obtain data or information about such structures and functions from the patient at specified, discrete locations along the length of a patient. Using this information, the camera produces a series of images, each depicting a cross-section of the body of the patient, in a plane generally perpendicular to the length of the patient, and at specified points along the length of the patient. Combined, successive images or a substantially continuous spiral image taken along the length of a patient can yield a relatively three-dimensional view of internal organs and tissues, or at least provide a cross-sectional view of bodily structures or functions at various places on the patient. Tomographic cameras are most frequently used to view and treat organs and other tissues within the head, torso and trunk of a patient and, in particular, diagnose and treat such ailments as heart disease, arteriosclerosis, cancer, and the like.
Tomographic imaging cameras are often identified by the “mode” or “modality” of radiation used by their scanners to obtain patient data. Well-known scanner modalities include the X-ray Computed Tomography (CT), Magnetic Resonance Imaging (MRI), Ultra-sound (ULT), Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) scanners. Camera systems which combine two or more different scanners to obtain a greater variety of imaging information from a patient are referred to as “multimodality imaging systems.” Conversely, tomographic cameras utilizing the same mode to collect imaging information are referred to as having the same modality.
A tomographic camera utilizes a scanner having an array of radiation detectors forming a ring or bore that surrounds a patient. The scanner gathers information along a plane defined by the detector ring, which intersects the patient substantially perpendicularly to the length of the patient. Other processors and instruments coupled to the scanner form the tomographic image, based on information received from the scanner. To obtain information at successive points along the head, torso and trunk of a patient, the patient is supported horizontally on a patient table that translates or moves the patient horizontally through the bore of a tomographic camera.
It is often desirable to utilize two or more adjacent tomographic scanners of different modalities, in multimodality systems, to obtain a variety of imaging information from a single traverse of a patient through multiple scanner bores. This is highly desirable as a means of increasing efficiency (by completing two or more scans in one operation), increasing the accuracy of indexing, correlating or linking multimodality images to the same location along the length of the patient (by coordinating operation of the scanners to a single, controlled movement of the patient) and reducing the labor costs otherwise associated with separate, multimodality scanning operations.
In general, multimodality systems include a series of scanners, each having a different modality, supported by a single housing. Each scanner obtains different information about the patient, which, when combined, provides a better understanding of the patient. More specifically, multimodality cameras typically include a scanner of anatomical structures of the patient (e.g., CT, MRI and Ultrasound cameras) and a scanner of physiologic functions of the patient (e.g., SPECT and PET cameras). The series of scanners forms a relatively long bore, typically longer than the combined head and torso of taller patients and spanning the entire length of shorter patients. The patient is moved at a relatively slow rate through the lengthy multimodality scanning bore, while imaging information is obtained.
The residence time of a patient within the multimodality scanner bore closure typically is in the range of from less than a minute to as much as an hour or more. During much or all of this time, the patient is isolated from operators of the multimodality scanners and cameras, from caregivers who may need to treat the patient, adjust instruments connected to the patient, or perform interventional applications (i.e., image-guided biopsies and the like), and from caregivers who might otherwise attend to the patient, should the patient become upset or ill from ingested radio-pharmaceuticals, and the like. Moreover, the relatively lengthy isolation of the patient within the tight quarters of the bore can cause anxiety, such as claustrophobia, and other discomfort or stress in the patient.
These shortcomings of multimodality cameras make their use less desirable when all modalities of imaging are not required. For example, in the event use of only the first scanner of a multimodality system is needed, such as use of a CT scanner forming the front portion of the scanner bore, the patient will remain within the scanner bore. In that circumstance, the extended length of the bore forming an imaging area for the PET scanner is unused. Nevertheless, should interventional applications or other procedure require direct access to a patient by a caregiver, additional time and effort will be required to extend or withdraw the patient from either end of the multimodality scanner bore. Moreover, unnecessary levels of patient discomfort, stress and anxiety result.
Accordingly, there is a need for a multimodality tomographic imaging system that allows use of less than all scanners and corresponding adjustment of the length of the scanner bore, to provide more immediate patient access and to reduce the time and effort needed to handle or attend to the patient.